SlidesPPT - Beautiful free presentation templates for Google Slides
Imakiku - Imakiku is an audience response system for real-time voting, posting comments, and surveying.
Slidebean - Presentations that design themselves
Pingo - Optimize images for the web quickly 🖼️⚡
Selfone - Free template for PowerPoint, Keynote and Google Slides
Blooket - Blooket is an interesting application that provides you with a wide range of features to create activities for class engagement.